Speech and sound learning apparatus has been available in market in a number of different forms. For example, SPEAK & SPELL, SPEAK & MATH, and SPEAK & READ, all being trademarks of Texas Instrument Incorporated, which show questions on display means and receives answer inputted from keyboard. The devices then provide correct answers. Some of the speech and sound learning apparatus also provide communication of synthesized audio signals to help the operator to learn.
The input means, keyboard, of these devices is obviously difficult for young child user. To overcome such a problem, optical code reading devices, such as bar code reader, are used to replace the keyboard input for reading symbols. In some devices, electronic speech synthesizer is also incorporated to provide communication with the operator or user with synthesized speech. A typical example is U.S. Pat. No. 4,337,375 issued on Jun. 29, 1982 to Freeman, entitled "Manually Controllable Data Reading Apparatus for Speech Synthesizers", which uses optical codes to identify speech factors, such as phoneme, identity, inflection, duration and syllabic identity. The optical codes are read by optical code reader and stored in buffer memory and then spoken out by speech synthesizer.
U.S. Pat. No. 4,375,058, issued on Feb. 22, 1983 to Bouma et al., entitled "Device for Reading a Printed Code and for Converting This Code into an Audio Signal" discloses a device which uses optical code reader to read optical code and stores this code in an intermediate memory to be directly transmitted to speech synthesizer for generation of audio signals. Alternatively, the contents of the intermediate memory is a memory address in which the information of an object is stored. The object memory is then accessed by speech synthesizer to generate audio signals. The information supplied to the speech synthesizer is still those speech factors mentioned previously. Other electronic learning aids using optical input and synthesized speech output include U.S. Pat. No. 4,457,719 to Dittakavi et al. which provides sequencing and spelling exercises audibly, U.S. Pat. No. 4,466,801 to Dittakavi et al. which is capable to repeat an element of non-spoken sound and to generate a relatively long sound effects from short coded indicia, U.S. Pat. No. 4,505,682 to Thompson which provides functions of matching and comparing, U.S. Pat. No. 4,549,867 to Dittakavi et al. which may shore a number of sound identifications generated by passing the optical reader over a sequence of bar codes in queue memory to allow them to be spoken out sequentially or alternatively, produces an audible random sequence of sounds and asks an operator to the use optical code reader to select the right sequence of the codes with a number of optical codes and the device will indicate if it is correct.
The above-described prior art technique uses either keyboard or optical code reader as input means and generates output with synthesized speech to enhance the learning effectiveness. The synthesized speech, although quite close to human voice and good enough to have people understand, is different from the human voice. For an operator wishing to learn correct pronunciation of a language, this is quite a deficiency. Therefore, under such a situation, true human voice is the only choice. U.S. Pat. No. 5,059,126 issued on Oct. 22, 1990 to Kimball, entitled "Sound Association and Learning System" discloses a device which speaks with true human voice. However, Kimball uses compact discs (CD) to store the true human voice and uses a CD player to play back the contents of the CDs. A disadvantage is that the CD player is quite sensitive to shock and vibration and if it is to be operated by a young child, the CD player will be easy to damage.
Besides, the conventional device using optical code reader as input means and adapting synthesized speech as output means has another disadvantage that is that the length of the optical code depends upon the contents of the speech factors and thus for a lengthy sentence, the optical code may be too long to be printed in a single line. This is obviously inconvenient.